Thermodynamic Performance Enhancement of a Natural Gas-Fired Power Plant Using Gas Path Diagnostics and Joule Thomson-Based Intake Air Cooling

Abstract

Gas turbine performance decreases significantly under elevated ambient temperatures due to reduced compressor inlet air density and increased thermodynamic losses along the gas path. This work presents a thermodynamic performance assessment and enhancement analysis of a utility-scale natural-gas-fired gas turbine using actual operational data. Baseline evaluation shows progressive reductions in output and efficiency with increasing ambient temperature. Gas-path analysis based on Brayton-cycle relations identified increased compression work associated with elevated inlet temperatures. To mitigate these losses, cooling potential generated during natural-gas pressure reduction was utilized through a Joule–Thomson-assisted intake air cooling arrangement. Ambient air temperatures of 25.84–30.88 °C were reduced to 15.67–20.11 °C, producing inlet temperature reductions of 9–11 °C. Net power output increased from 137.14–147.86 MW to 151.63–161.61 MW (8.65–10.57%), while heat rate decreased by 2.3–2.7%, specific fuel consumption reduced by about 4.55%, and thermal efficiency improved by up to 2.8%. The combined gas-path diagnostic and JT-assisted cooling approach demonstrates a practical low-energy retrofit option for improving gas turbine performance under high-temperature operating conditions without additional water or auxiliary power consumption. The methodology involved baseline performance evaluation using operational data, Brayton-cycle-based gas-path diagnostics, and modeling of Joule–Thomson-assisted intake air cooling using literature-adopted thermodynamic parameters.